The 4-hydroxycinnamic acid compounds are secondary metabolites biosynthesized in plants mainly in the shikimic acid pathway and are compounds serving as raw materials of substances whose physiological activity have been reported in a large number of reports, such as phenyl propanoid, flavonoid, lignan, and tannin. The 4-hydroxycinnamic acid compounds themselves are also compounds which are biosynthesized from plants in order to protect the plants themselves and seeds from ultraviolet rays and a large amount of which are present in the nature. With respect to flavonoid, lignan, and the like which are polymers of the 4-hydroxycinnamic acid compounds, a large number of compounds having physiological activity are present and foods containing the same are eaten for health enhancement.
The hydroxystilbenes are secondary metabolites biosynthesized in the shikimic acid pathway in plants. For example, resveratrol, piceatannol, pterostilbene, and the like are mentioned. The physiological activities thereof have been reported in a large number of reports and they are compounds which draw particularly high attention. The hydroxystilbenes are contained in grapes and berries in a relatively high proportion and a large number of foods, supplements, and the like containing the same are commercially available. Polymers thereof are similarly contained but the content thereof is very small, and thus physiological activity cannot be expected.
As the 4-hydroxycinnamic acid compounds and derivatives of hydroxystilbenes, substances are hardly mentioned except polymers. As the hydroxystilbene derivative, alkylether and ester phosphate have been merely examined (Patent Document 1).
With respect to hydroxystilbene, flavonoid, lignan, and the like, various physiological activities have been reported. However, purifying the compounds from natural products poses a large number of problems in terms of cost and working efficiency. Further, a large amount of trace constituents are included. Therefore, a process for easily obtaining the same has been desired.